A display device, which displays various information such as an electronic book, a still image and video image, is proposed. As a representative such display device, a tablet-shaped computer and an electronic book are offered. Such a display device is operated in the state held by hand of the user. When the display device displays the electronic book, such a display device detects the operation of the finger of the user by a sensor, and, depending on this detecting result, controls, for example, a turn of a page of the electronic book.
One method to use a touch panel provided in a display screen is proposed as a method to detect the operation of the finger of the user. In addition, another method to use a bend detecting sensor which detects a bend power added to the display device and is provided in the display screen in the flexible device, is proposed as a method to detect the operation of the finger of this user.